Enhanced alginate capsule properties as a formulation of entomopathogenic nematodes

Despite many advantages of employing entomopathogenic nematodes (EPNs) as biocontrol agents against soil-dwelling insect pests, their use is still limited to home gardening or small-scale farming. Lack of cost-effective, durable formulations, as well as appropriate application methods have so far prevented the use of EPN in large-scale farming. A recent report on alginate capsules as a novel EPN formulation for application into the soil shows promise. However, EPNs often readily escaped from these capsules within a few days especially when they are not refrigerated. To improve EPN retainment, we adjusted capsule properties by changing the reaction temperature for capsule formation and by adopting post-treatment of alginate capsules with excessive Ca²⁺, and then evaluated EPN escape from the capsules manufactured under different conditions. While capsules with the hardest capsule shell were produced at 4 °C with the Ca²⁺ post-treatment, the 40 % enhanced EPN retainment was achieved only by lowering the reaction temperature.